The Viral Studies Section (VSS), Viral Epidemiology Branch (VEB), Epidemiology & Biostatistics Program (EBP), Division of Cancer Etiology (DCE), National Cancer Institute (NCl), is continuing the conduct of this study to define the prevalence of HTLV-l and HIV infection in the normal Trinidadian population using already existing serum collections and collections to be made under this contract to systematically collect samples and information in lymphoreticular malignancies, to develop and follow cohorts at high risk for HlV (homosexuals, prostitutes, etc.), and to evaluate risk factors from virus infection and disease outcome with particular emphasis on HTLV-l and HlV interaction. Both shall be followed to an historic cohort of the normal Barbados population infected with HTLV-l to evaluate long-range health effects of the virus.